Injectable in situ polymerizable collagen composition

ABSTRACT

The present invention is directed to injectable acid soluble collagen compositions comprising a neutralized solution of an acid soluble collagen, EDTA and preferably a polyol, wherein the composition is injectable at physiological pH and the acid soluble collagen polymerizes upon exposure to tissue. The invention is suitable for use in soft tissue augmentation, promoting soft tissue regeneration and coating medical implants and devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority to U.S. ProvisionalApplication Ser. No. 61/851,119 filed on Mar. 4, 2013, which is herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to the field of collagen compositionsand their methods of use.

2. Description of Related Art

Collagen compositions have been utilized for more than 30 years toaugment or smooth out soft tissue defects such as dermal wrinkles anddermal folds, to volumize furrows, or to correct dermal contourunevenness and laxity.

The collagen compositions utilized for soft tissue augmentation havebeen comprised of either reconstituted collagen fibrils prepared fromsolubilized collagen extracted from animal hides, reconstituted collagenfibrils prepared from soluble recombinant human collagen or intactcollagen fibrils or fibers processed from human skin. In all cases thecollagen composition has been composed of collagen fibrils/fibers orcrosslinked collagen fibrils/fibers.

Since soft tissues are primarily composed of collagen-based matrices, itmakes sense to correct soft tissue defects with collagens orcollagen-based compositions. There have been at least twelve FDAapproved collagen products available for soft tissue augmentation in theU.S. since 1981. These products are generally called dermal fillers.However, at this time, most of the collagen-based fillers are no longeravailable in the U.S. market. They have been replaced by compositionsthat provide more durability including hyaluronic acid products, andproducts containing hydroxylapatite microbeads, poly-L-lactic acidparticles, and polymethylmethacrylate microspheres.

There is still interest in having improved collagen-based compositionsavailable for soft tissue augmentation. However, the compositions mustexhibit increased durability.

BRIEF SUMMARY OF THE INVENTION

In certain embodiments, the invention is directed to an injectable acidsoluble collagen composition comprising, a neutralized solutioncomprising the acid soluble collagen, EDTA and a polyol, wherein thecomposition is injectable at neutralized pH, and the acid solublecollagen polymerizes upon exposure to ion-containing fluids.

In certain embodiments, the invention is directed to a method foraugmenting soft tissue, comprising injecting into a soft tissuedeficiency an acid soluble collagen composition comprising, aneutralized solution comprising the acid soluble collagen and EDTA,wherein the composition is injectable at neutralized pH and wherein theacid soluble collagen polymerizes upon exposure to the tissue. Incertain embodiments of the invention, the injected composition producesregeneration of the tissue.

In certain embodiments, the invention is directed to biocompatiblemedical implant, wherein the implant is comprised of a polymer or metal,and a coating of a neutralized acid soluble collagen compositioncovering at least a portion of the implant, wherein the collagencomposition is solidified on the surface of the implant.

Additional aspects of the invention, together with the advantages andnovel features appurtenant thereto, will be set forth in part in thedescription which follows, and in part will become apparent to thoseskilled in the art upon examination of the following, or may be learnedfrom the practice of the invention. The objects and advantages of theinvention may be realized and attained by means of the instrumentalitiesand combinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a and 1 b depict polymerization of the composition of oneembodiment of the present invention in saline.

FIG. 2 depicts implants of the composition of one embodiment of thepresent invention in rat dermis at 6 months.

FIG. 3 depicts an implant of the composition of one embodiment of thepresent invention in rat dermis at 6 months.

FIG. 4 depicts an implant of the composition of one embodiment of thepresent invention in rat dermis at 6 months.

FIG. 5 depicts a TEM photomicrograph of a collagen fibril of oneembodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

The present invention relates to a unique collagen composition withapplications for soft tissue augmentation and tissue regeneration, amongother uses. The present invention is directed to injectable acid-solublecollagen compositions comprising a neutralized solution of an acidsoluble collagen, EDTA and a polyol, wherein the composition isinjectable at physiological pH and the acid-soluble collagen polymerizesupon exposure to tissue. In certain embodiments, the injectable, in situpolymerizable soluble collagen compositions are in the form of clear,injectable, viscous solutions at neutral pH. The compositions rapidlyundergo polymerization involving initial gelation and subsequentfibrillization when contacted by or mixed with physiological fluids orother ion-containing fluids to form fibrous collagen matrices.

The collagen compositions are chemically treated with EDTA to producetemperature stable viscous solutions at neutral pH that exhibitanti-collagenase and anti-microbial characteristics. In addition,polyols, such as D-mannitol or other polyol osmolality enhancers, arepreferably added to bring osmolality to physiological levels and to aidin stabilizing the soluble collagen composition during storage. TheD-mannitol also improves biocompatibility. Sucrose, fructose, and otherdisaccharides may also be added to aid in stabilizing the compositionduring storage.

The compositions are suitable for use in soft tissue augmentation andpromoting tissue regeneration. Anti-collagenase characteristics reduceor prevent digestion by tissue enzymes and anti-microbialcharacteristics provide additional assurance of sterility and preventionof biofilm formation. The compositions are also useful for coatingmedical implants.

The present invention further includes methods for augmenting softtissue and tissue regeneration using in situ polymerizing collagencompositions of the present invention. The compositions are preferablyin the form of a clear viscous, soluble, biocompatible collagen atneutral pH that can be easily injected through small needles (eg. 27 or30 gauge) and upon injection into tissues rapidly undergo gelation andsubsequent fibril formation. Upon interacting with tissue fluids, thecomposition nearly instantly forms a cohesive clear gel containingcollagen molecular units that rapidly undergo fibril formation to forman opaque collagen matrix. In addition, the composition has been treatedto include disodium EDTA in sufficient levels to impart anti-collagenaseand bactericidal activity. It has been found that the in situ formedcollagen matrix unexpectedly exhibits unique properties that prolongdurability beyond that of known injectable collagen fillers. The EDTAimparts anti-collagenase activity by inhibiting tissuemetalloproteinases that digest interstitial collagen and collagenmatrices. It also imparts bactericidal activity to provide additionalcomposition sterility and potentially inhibit biofilm formation.

The compositions of the present invention have shown durability andretained injection volume, with little or no reduction in originalinjection volume, for time periods of 4 weeks, 12 weeks and beyond 6months. This property is different from most hyaluronic acid gels thatincrease in volume upon injection and then gradually lose volume over aperiod of months. In certain embodiments, upon injection into tissue,such as dermal tissue, the in situ polymerizing collagen compositionforms a fibrous mass that integrates with surrounding tissue matrices.

Certain terms have the following meanings as use herein:

By “collagen” it is meant all types of collagen including those whichhave been processed or modified. The collagen may be of human or animalorigin or may be produced using recombinant techniques. As used herein,collagen includes purified collagens as well as various collagenderivatives.

By “tissue” it is meant an aggregation of similarly specialized cells inan organism, preferably mammalian, and, most preferably human, where thecells are exposed to the organism's extracellular fluid.

By “in situ polymerization” it is meant formation of a cohesive collagengel, and subsequently a collagen fibrillar mass, upon injection of thesoluble collagen into tissue and not before injection.

By “gel mass” it is meant the clear gel that is formed immediately afterthe viscous collagen solution is injected into a physiologic solution orinjected into tissue or exposed to ions that initiate polymerization.The clear gel mass becomes more opaque as it converts into a cohesivefibrillar collagen mass within minutes after making contact withphysiologic fluids.

The collagen used to prepare the in situ polymerizing collagen may beextracted from animal hides, such as bovine hide or porcine hide, or maybe cell derived human collagen, or recombinant human collagen. It ispreferred that the base collagen be available in acid solution. Any acidsoluble, fibril forming collagen type may be used. However, Types I andIII collagen are preferred to prepare the in situ polymerizing collagencomposition.

In one embodiment of the present invention, a neutralized, acidsolubilized collagen, which remains in solution at physiologicaltemperatures, is used in the in situ polymerizing collagen of thepresent invention. One method for initial treatment of the collagen toform such solution is disclosed in U.S. Pat. No. 5,492,135, which isincorporated herein by reference. In one embodiment, the solublecollagen may be isolated and purified from animal sources includingbovine and porcine tissues or may be a recombinant human collagen. Theresulting acidic collagen solution is preferably extensively dialyzedagainst disodium EDTA solutions to prevent premature collagenfibrillogenesis. During step-wise dialysis, the pH of the collagensolution is increased from acidic levels to a neutralized pH byadjusting the pH of the disodium EDTA dialysis solutions using 1N sodiumhydroxide. The resulting neutralized pH is preferably between about 6.8and about 7.5. At a neutralized pH, the collagen preparation does notundergo typical fibrillogenesis and remains clear and transparent untilcontacted by physiologic, or other ion-containing, fluids.

The collagen is present in the composition of the present invention insufficient amounts to be injected through 27-31 gauge needles andcannula to provide effective tissue bulking, but not so concentratedthat it cannot be injected through at least a 27 gauge needle or cannulaor form a compact matrix that impermeable to host cells. In certainembodiments, the composition comprises the acid soluble collagen in aconcentration between 5 and 70 mg/ml (0.5-7.0% w/v), between 25 and 65mg/ml (2.5-6.5% w/v) or between 20 and 40 mg/ml (2-5% w/v).

The EDTA present in the composition is preferably disodium EDTA. TheEDTA remaining in the injectable composition after dialysis ispreferably present in sufficient concentration to provideanti-collagenase activity sufficient to inhibit activity of tissuemetalloproteinases and to provide bactericidal activity to assuresterility and potentially inhibit biofilm formation. In certainembodiments, the concentration of the EDTA in the injectable compositionis between 10 and 50 mM, between 25 mM and 40 mM, or between 30 mM and35 mM.

In certain embodiments, the compositions of the present inventioncontain a polyol to bring the composition to physiologic osmolality andto aid in stabilizing the soluble collagen composition during storage.The polyol may also produce improved biocompatibility. Osmolality ispreferably between 280 and 360 mmol/kg. In certain embodiments, thepolyol is a sugar alcohol or other osmolality enhancer, and ispreferably D-mannitol. In certain embodiments, the composition comprisesthe polyol in a concentration between 2.5% and 4%, or between 3.0% and3.9%, or 3.5%.

Disaccharides, such as sucrose or fructose, may be included in thecomposition to aid in stabilization of the viscous collagen solution. Incertain embodiments the disaccharides are added to a final concentrationof between 50 mM to 500 mM, or 100 mM to 400 mM.

The composition is a neutralized pH solution that allows for injectableadministration. In certain embodiments, the viscosity of the compositionis suitable for injection through a fine gauge needle or cannula, suchas a 27, 30 or 31 gauge needle or cannula. The low viscosity also allowsfor low extrusion forces. The composition can be injected through 27, 30or 31 gauge needles with no significant difference in extrusion force.In addition to the ease of application, injectable delivery of thecollagen solution allows access to the administration site whileminimizing invasive injury to surrounding tissues.

Upon exposure to physiologic liquids, tissues, or other ion-containingfluid, the collagen solution polymerizes. Preferably, the compositionundergoes rapid, nearly instant, gelation, followed by rapidfibrillogenesis to form a collagen fibril matrix. In certainembodiments, the composition initially polymerizes into a gel masswithin 180 seconds after exposure to tissue, or within between 10 and120 seconds or between 10 and 60 seconds after exposure to the tissue.

The composition forms a collagen fibril matrix rapidly after gelation.In certain embodiments, the collagen matrix is a white opaque masscomprising intact collagen fibrils. In certain embodiments, thecomposition forms a collagen fibril matrix within 10 minutes afterexposure to the tissue, or within 5 minutes after exposure to thetissue.

The viscosity of the collagen solution is sufficient to fill a softtissue defect or other specific delivery sites and remain in the desiredtissue site until gelation and fibril formation occurs. Also, because ofthe rapid gelation and matrix formation, the volume of the formedcollagen matrix is equivalent to the volume injected, making itconvenient for practitioners to make a more precise determination of theappropriate volume to treat a dermal defect. This is an advantage overmost hyaluronan injectable products that increase in volume afterinjection.

The present invention is also directed to a method for augmenting softtissue or regenerating tissue. The method comprises injecting aneutralized acid-soluble collagen composition into a soft tissuedeficiency, wherein the acid-soluble collagen polymerizes upon exposureto the tissue. Upon injection into tissue and contact with the tissuefluid, the composition undergoes rapid, nearly instant, gelation, whichis followed by rapid fibrillogenesis to form a collagen fibril matrix.The collagen fibril matrix fills the soft tissue deficiency. As usedherein, fill does not require that the deficiency be completely filled.However, completely filling the deficiency is also contemplated. Incertain embodiments the composition comprises EDTA in concentrationsdescribed above. The composition may comprise polyols in theconcentrations described above. In certain embodiments, the compositionpolymerizes and forms a collagen fibril matrix during the time periodsdiscussed above.

The method of soft tissue augmentation can be used with a variety ofsoft tissue deficiencies. Soft tissue defects that can be treated withthe method of the invention include wrinkles, dermal folds, dermallaxity, skin contour defects, dermal fine lines, dermal furrows anddermal unevenness. The composition can be injected into a variety ofdermal areas. The method is particularly well suited to be injected intoa soft tissue deficiency of lips or facial skin. The amount of thecomposition to be injected can be determined by one skilled in the artbased on the soft tissue deficiency being treated. In many applications,volumes of 0.1-0.5 mL may be used.

The method of the present invention provides an in situ collagen matrixthat is surprisingly durable. When used herein, a matrix remains durableif the collagen matrix does not degrade to a visually noticeable level.Durable in this context means the matrix remains intact and sufficientlymaintains its injection volume to provide long-term clinicaleffectiveness. The method of the present invention can produce acollagen fibril matrix that remains durable for at least 4 weeks aftersaid injection, at least 12 weeks and even 6 months or more. In certainembodiments, the collagen matrix produced by the method of the presentinjection integrates with the surrounding tissue, preferably byintegrating with the matrices of the surrounding tissue.

The present invention is also directed to a method of injecting acollagen composition as described herein to promote or enhance softtissue regeneration. The collagen matrix formed by the composition ofthe present invention provides a biological framework or matrix thatsupports and/or stimulates revascularization and cell population. Thissupports remodeling of the subject's own tissue.

The present invention is also directed to the use of a neutralized, acidsoluble collagen solution as a biocompatible coating for medicalimplants and devices, as well as to the method for coating the implantor device. Certain embodiments are directed to a biocompatible polymericor metallic medical implant or device, wherein the implant or devicecomprises a coating formed by a collagen composition described herein.In certain embodiments the device or implant is comprised of stainlesssteel. The coating may cover a portion or all of the implant or device.The coating comprises a neutralized solution comprising the acid solublecollagen, wherein the collagen is solidified on the surface of theimplant or device. Although not wishing to be bound by any one theory,it is believed the collagen is fibrillized either through directdivalent ion exchange with the surface of the implant or device, or bydrying on the surface of the implant or device. The composition may alsocomprise one or both of EDTA and polyols as described herein. In certainembodiments, the coating is stable on the implant for at least 30 days.

The invention is also directed to a method for applying an in situpolymerizing collagen solution disclosed herein to a medical implant ordevice. The solution can be applied by any means known in the art,including by dip coating or spray coating. After approximately 30minutes, a thin, transparent coating forms on the material. The coatingis strong and durable and hard to scrape off the implant or device.Application of such coatings is expected to add to biocompatibility,improve resistance to biodegradation, reduce delamination concerns,promote tissue adhesion, reduce rejection and potentially addanti-microbial properties to the polymer or metallic implants anddevices. The coating may also fill small grooves in the implant ordevice and create an even and smooth coating.

The present invention provides a number of advantages over othercollagen-based compositions for soft tissue augmentation. For example,the collagen compositions described herein are biocompatible,biodegradable, and stable in solution at neutral pH. The composition ischaracterized by in situ formulation of a collagen matrix, unlike othercollagen-based compositions that polymerize before implantation. Thepresent invention does not require use of crosslinking agents,additional fibrillar components, or synthetic polymers. The ability tochemically manipulate the collagen to form a neutral pH stable solutionallows for injectable administration through a fine gauge needle. Inaddition to the ease of application, injectable delivery of the collagensolution allows access to the administration site while minimizinginvasive injury to surrounding tissues. The viscosity of the collagensolution is sufficient to fill a soft tissue defect or other specificdelivery sites and remain in the desired tissue site until gelation andfibril formation occurs. The volume of the formed collagen matrix isequivalent to the volume injected making it convenient for practitionersto make a more precise determination of the appropriate volume to treata dermal defect. This is an advantage over most hyaluronan injectableproducts that increase in volume after injection. The addition ofdisodium EDTA provides anti-collagenase activity to inhibit tissuecollagenases and other metalloproteinase to prolong the durability ofthe collagen implant and bactericidal activity to provide compositionsterility and to prevent potential biofilm formation. The addition ofD-mannitol, or similar sugar alcohols, brings the composition tophysiologic osmolality and aids in stabilizing the composition beforeinjection into tissues or application as a coating. In vivo studies inanimal models have demonstrated maintenance of soft tissue augmentationfor at least 6 months. Compositions aseptically prepared with disodiumEDTA have generally been shown to be sterile. Contributions fromdisodium EDTA may have contributed to the ability to provide sterilecompositions. In addition, the composition has exhibited the ability topromote tissue regeneration without use of therapeutic agents, stemcells or other added growth stimulators.

Certain aspects of the present invention are illustrated by thefollowing non-limiting examples.

Example 1 Preparation of In Situ Polymerizing Compositions by DialysisAgainst a Single EDTA Solution Sequentially pH Adjusted

The in situ polymerizing collagen compositions were prepared usingmethods based on those described by DeVore and Eiferman (U.S. Pat. No.5,492,135). Pure, soluble, bovine Type I collagen was purchased fromAdvanced BioMatrix, Inc. Sodium chloride was added to the soluble,pepsin-digested collagen solution (3 mg/mL) to a concentration of 0.8Mto precipitate collagen. The white, opaque precipitate was recovered bycentrifugation for 30 minutes at 3500 RPM and concentrated toapproximately 40 mg/mL by placement on filter paper to absorb excessliquid. The concentrated collagen precipitate was placed in dialysistubing with a molecular weight cut-off of 100,000 daltons and dialyzedagainst 0.5M acetic acid for at least 16-18 hours and then 0.1M aceticacid for at least 16-18 hours. The resulting clear, viscous, redissolvedcollagen concentrate was then dialyzed against 0.035M (35 mM) EDTA(ethylenediaminetetraacetic acid, disodium salt dihydate, SigmaUltra˜99%). It was important to dialyze against disodium EDTA concentrationsof at least 25 mM and preferably as high as 35 mM. Dialysis wascontinued for 5 days with daily adjustment of pH from the starting pH of4.5 to a final pH of 7.5. The final clear and viscous collagenconcentrate was collected and centrifuged to remove air bubbles. Thefinal clear, viscous collagen exhibited a pH of 7.4 and did not undergofibril formation at room temperature. Collagen fibrillogenesis was nottriggered until the collagen was exposed to physiological liquids orliquids containing ions to trigger gelation and polymerizing reactions.

Evaluation of Gelation and Fibril Formation.

Aliquots of the in situ polymerizing collagen prepared as describedabove in this Example 1 were injected into 0.8M sodium chloride at 37°C., as depicted in FIG. 1 a. Test samples were observed for theappearance of gel and fibrous collagen. As shown in FIG. 1 b the clearviscous collagen solution formed a white, opaque collagen matrix in lessthan 60 seconds.

Example 2 Evaluation of a Human Skin Biopsy

Approximately 0.2 cc of in situ polymerizing collagen prepared asdescribed in Example 1 was injected into the dermis of the hand. Abiopsy was removed at 4 weeks and processed for H&E staining.Histological evaluations show exceptional biocompatibility withnegligible inflammatory reactivity and clear integration by hostfibroblasts.

Example 3 Evaluation of Injecting In Situ Polymerizing Collagen in RatTissues

Soluble, pepsin digested, bovine collagen was purchased from AdvancedBiomatrix. In situ polymerizing collagen was prepared as described inExample 1 by extensive dialysis of salt precipitated, concentrated andacid treated collagen against 35 mM EDTA with step-wise increase in pHto 7.5. Collagen concentration was 37 mg/mL as assayed by hydroxyprolineanalysis. The rats were injected at 4 dermal sites with 0.4 cc each ofin situ polymerizing collagen. Injection sites were examined forerythema and edema daily for 1 week, and then weekly for to 6 months.The animals were terminated at 2 weeks, 1 month, 3 months, and 6 months.The rat skin was removed and implant sites examined macroscopically andphotographed before dissection and preparation for histologicalassessment. Sections were stained with H&E and photomicrographs takenfor evaluation. Evaluation of the underside of rat dermis clearly showedthe opaque, collagen implant sites at each time period (FIG. 2). Thecollagen implant was clearly observed in H&E stained sections at eachtime period with little change in implant volume. Inflammatory cellreactivity was negligible to minimal and the implant itself was composedof an organized collagenous structure with fibroblastic cellularinfiltrates (FIGS. 3 and 4).

Example 4 Preparation of In Situ Polymerizing Collagen Compositions byDialysis Against Multiple, pH Adjusted EDTA Solutions

Pure, soluble, porcine Type I collagen was purchased from SunMaxBiotechnology, LTD. Saturated sodium chloride solution was added to thesoluble, pepsin-digested collagen solution (3 mg/mL) to a concentrationof 0.8M to precipitate collagen. The white, opaque precipitate wasrecovered by centrifugation for 15 minutes at 5000 RPM. The concentratedcollagen precipitate was placed in dialysis tubing with a molecularweight cut off of 10,000 daltons, or in dialysis cassette with amolecular weight cut-off of 20,000 daltons, and dialyzed against 0.5Macetic acid for at least 16-18 hours and then 0.1M acetic acid for atleast 16-18 hours. The resulting clear, viscous, redissolved collagenconcentrate was then dialyzed against 0.035M (35 mM) EDTA(ethylenediaminetetraacetic acid, disodium salt dihydate, SigmaUltra˜99%). It was important to dialyze against disodium EDTA concentrationsof at least 25 mM and preferably as high as 35 mM. The starting pH was5.0±0.2. Dialysis was continued for at least 12 hours. The dialysistubing or cassette was then transferred into a dialysis chambercontaining 35 mM EDTA at a pH of 5.5±0.2 and dialyzed for at least 12hours. The dialysis tubing or cassette was again transferred into adialysis chamber containing 35 mM EDTA at a pH of 6.0 and dialyzed forat least 12 hours. Subsequent dialysis steps against 35 mM EDTA at pH6.5 and 7.2 were conducted to bring the final collagen pH toapproximately 7.0. The final clear, viscous collagen exhibited a pH ofapproximately 7.1 and did not undergo fibril formation at roomtemperature. Collagen fibrillogenesis was not triggered until thecollagen was exposed to physiological liquids or liquids containing ionsto trigger gelation and polymerizing reactions.

Example 5 Effects of D-Mannitol on Stability of In Situ PolymerizableCollagen

Collagen solutions prepared as described in Example 4 were subject to afinal dialysis step against 35 mM EDTA containing 3.8% D-mannitol (346mmol/kg). Stability (maintenance of clarity and transparency) ofcollagen solutions containing D-mannitol was compared to collagensolutions without D-mannitol by incubating solutions at 36° C. Stabilitywas assessed by observing the visual appearance of the collagensolutions up to 225 minutes. Results demonstrated that D-mannitolsignificantly extended the stability of collagen solutions (at least 225minutes) compared to controls (75 minutes).

Example 6 Improvement of Intracutaneous Irritation Scores with In SituPolymerizable Collagen Containing D-Mannitol

Intracutaneous irritation testing in rabbits based on ISO 10993-10 wasconducted at NASMA. Test samples included in situ polymerizable collagenprepared as described in Examples 4 and 5, except that the process ofExample 5 included a final dialysis step against 3.5% D-mannitol. A 0.1ml dose of the test samples was injected intracutaneously in fiveseparate sites in the backs of 3 animals for each composition.Additional positive control samples and negative controls were alsotested. Injection sites were examined for erythema and edema immediatelyafter injection and at 24, 48, and 72 hours after injection.Observations continued at 24 hour intervals for up to 7 days afterinjection. Test scores for in situ polymerizable collagen solutionwithout D-mannitol were similar to the positive control sample. However,test scores of in situ polymerizable collagen with D-mannitol were lowerthan test scores without D-mannitol; 0.7 for compositions withD-mannitol compared to 1.4 for compositions without D-mannitol, based onthe rating scale in the NASMA study protocol. These results wereunexpected and indicate that addition of D-mannitol enhances thebiocompatibility of the in situ polymerizable compositions.

Example 7 Effect of Sucrose on Stabilization of In Situ PolymerizingCollagen Solutions

Collagen solutions prepared as described in Example 4 were subject to afinal dialysis step against 35 mM EDTA containing 3.5% D-mannitol and100 mM sucrose. This composition was compared to the collagen solutionsubject to final dialysis step against D-mannitol in Example 5. Solutionstability (time that solutions remained clear and transparent) at 37° C.was assessed by observing the visual appearance of the collagensolutions. Solutions dialyzed against 3.5% D-mannitol and 100 mM sucroseexhibited a significant increase in stability compared to solutionsdialyzed against D-mannitol alone. In one assay of stability, solutionsdialyzed against 3.5% D-mannitol and 100 mM sucrose exhibited a 4-foldincrease in stability compared to solutions dialyzed against D-mannitol.This observation suggests that long-term room temperature (20-25° C.)stability of the in situ polymerizable collagen will be significantlyenhanced by inclusion of sucrose.

Example 8 Evaluation of In Situ Polymerizing Collagen in RabbitIntradermal Tissue

Under general anesthesia, three Sprague-Dawley Rats were implanted witha sample of Monomer bovine collagen (RPC bovine) prepared according tomethods described in Example 4 and one control article (Restylane)through deep intradermal injection. The injections were placed 2 cmapart along the vertebral axis with three sites on each side (6 totalincluding other test samples) per animal. Test and control articles wereinjected into the designated dosing locations at a volume of 0.15-0.25mL per site.

Clinical observations and skin scoring (erythema and edema) wereconducted immediately following injection and prior to termination,after which one designated animal was euthanized at 2, 5 and 8 weeksrespectively. Daily observations were performed for the duration of thestudy. Following termination, the implant sites and draining lymph nodes(if identified) were collected, grossly evaluated for irritation andsubmitted for histopathology.

Overall, injection of in situ polymerizing collagen into the rabbit earmodel resulted in minimal to mild irritation and inflammation. Tissueresponses were equivalent to the tissue responses to the control.

Example 9 Evaluation of In Situ Polymerizing Collagen in Rabbit forLocal Tissue Response

In situ polymerizing porcine collagen solution prepared as described inExample 4 was injected in the subcutaneous tissue of the rabbit and thelocal tissue response was evaluated in accordance with ISO 10993 6,Biological evaluation of medical devices—Part 6: Tests for local effectsafter implantation.

The in situ polymerizing porcine collagen solution, a sponsor providedcontrol article and a negative control article, along with locationmarkers, were subcutaneously implanted and three animals (per interval)were euthanized at 4 weeks and 12 weeks. The subcutaneous tissues wereexcised and the implantation sites examined macroscopically. Amicroscopic evaluation of representative implantation sites from eachanimal was conducted to further define any tissue response.

The macroscopic reaction was not significant as compared to the sponsorprovided control and negative control articles at 4 and 12 weeks.Microscopically, the test article remained intact and was classified asa nonirritant as compared to the sponsor provided control and negativecontrol articles at 4 and 12 weeks. Additional microscopic analysis oftest specimens demonstrated maintenance of volume from 4 to 12 weeks andintegration with surrounding tissues.

The clinical observations and histological results presented in Examples2, 3, 6, 8, and 9 demonstrated the exceptional biocompatibility and invivo durability of the novel in situ polymerizing collagen in situpolymerizing collagen composition. Durability at 6-months shown inExample 3 exceeds that clinically reported for most injectable,collagen-based compositions for soft tissue augmentation.

Example 10 Transmission Electron Microscopy of Polymerized In SituPolymerizing Collagen

Polymerization Protocol: Approx. 0.1 mL in situ polymerizing collagenprepared as in Example 4 was added to 1 mL of 2× phosphate bufferedsaline at pH 7.2 at 35 C in a microcentrifuge tube. After 8-10 minutes,polymerized collagen samples were pipetted (a drop) onto a mini-grid (˜2mm in diameter) at the TEM prep lab. Then the excess was wicked off tocreate a thin film. A contrast agent was added for TEM analysis. TEMphotomicrographs showed well banded intact collagen fibrils (FIG. 5).

Example 11 Demonstration of Anti-Collagenase Activity

This study was conducted to determine collagenase inhibition of in situpolymerizable collagen compositions. Pure collagen fibrils served as acontrol article and the test collagen solution prepared as described inExample 4 was polymerized before testing to mimic a similar condition invivo. Hydroxyproline assays were performed before collagenasedegradation in order to ensure that the same amount of collagen was usedin the study. A hydroxyproline assay was performed after the collagenasedegradation to measure the collagen residue after reaction.

Results showed that the test collagen containing 35 mM EDTA wasapproximately 35% more resistant to collagenase digestion compared to astandard collagen sample.

Example 12 Demonstration of Bactericidal Activity

This study was conducted to evaluate bactericidal activity of in situpolymerizable collagen compositions. Two test samples of in situpolymerizable collagen, Lot 0022, prepared as described in Example 4,were exposed to Staphylococcus aureus. The test samples were polymerizedto form a scaffold before testing to mimic a similar condition in vivoAntimicrobial effects were evaluated by SEM imaging. Samples wereexposed to the bacteria solution (˜100 CFU/mL) for 2 days. Collagenscaffolds were removed from bacteria solutions, rinsed in 1× phosphatebuffered saline and treated with a fixative solution (2%paraformaldehyde and 2% glutaraldehyde in 0.1M cacodylate buffer) andrinsed with pure water before imaging. SEM photomicrographs clearlydemonstrated absence of bacteria colonies.

Example 13 Use of In Situ Polymerizing Collagen Solution as a Coating

Five different materials were coated with in situ polymerizing collagensolution.

1. Stainless steel plates (smooth and surface roughened using 50 and 220grit sandpaper)

2. Titanium bone screw

3. Polypropylene suture (Prolene)

4. Polypropylene mesh (lightweight, Bard)

5. PEEK (polyether ether ketone) bone screw (Smith and Nephew)

The viscous, soluble collagen resulted in a thick coating on all thematerials. The samples were placed in petri dishes to polymerize anddry. Upon drying the coatings were very thin, transparent, and verydifficult to see on some of the material specimens.

The films were characterized using at least one of the followingmethods:

1. Brightfield microscopy—A Nikon inverted microscope was utilized tocapture the transparent coating of the RPC. The microscopy imagesprovided measurements of coating thicknesses.

2. Scanning Electron Microscopy (SEM)—SEM (secondary electron) imagingwas utilized to investigate the integrity and quality of the coatings.

3. FTIR Spectroscopy—Before and after scans were acquired of the polymermaterials to determine the presence of the collagen coating.

4. Drop Shape Analyzer—The surface energy of the metallic plates weredetermined before and after coating in order to determine changes incontact angle/surface energy.

5. Stability Testing—After polymerization of the coatings, the coatedmaterials were then placed in PBS and incubated for 30 days at 37° C. todetermine the stability of the coating. After 30 days, the materialswere removed and brightfield microscopy was performed in order todetermine coating stability and thickness.

Results showed the presence of a smooth, conforming collagen coating onpolymer sutures and polymer meshes. Similarly, polished stainless steelplates were effectively coated with the in situ polymerizing collagensolution. Overall, the in situ polymerizing collagen compositionpolymerized and adhered to both metallic and polymeric materials and wasstable after 30 days exposure to phosphate buffered saline at 37°.

From the foregoing it will be seen that this invention is one welladapted to attain all ends and objectives herein-above set forth,together with the other advantages which are obvious and which areinherent to the invention.

Since many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be understood that allmatters herein set forth or shown in the accompanying drawings are to beinterpreted as illustrative, and not in a limiting sense.

While specific embodiments have been shown and discussed, variousmodifications may of course be made, and the invention is not limited tothe specific forms or arrangement of parts and steps described herein,except insofar as such limitations are included in the following claims.Further, it will be understood that certain features and subcombinationsare of utility and may be employed without reference to other featuresand subcombinations. This is contemplated by and is within the scope ofthe claims.

We claim:
 1. An injectable acid soluble collagen composition comprising,a neutralized solution comprising the acid soluble collagen, EDTA and apolyol, wherein said composition is injectable at neutralized pH, andwherein said acid soluble collagen polymerizes upon exposure toion-containing fluids.
 2. The composition of claim 1, wherein saidcomposition comprises said acid soluble collagen in a concentrationbetween 5 and 70 mg/ml.
 3. The composition of claim 2, wherein theconcentration of said acid soluble collagen in said composition isbetween 25 and 65 mg/ml.
 4. The composition of claim 3, wherein theconcentration of said acid soluble collagen in said composition isbetween 20 and 40 mg/ml.
 5. The composition of claim 1 wherein said EDTAis disodium EDTA.
 6. The composition of claim 1, wherein saidcomposition comprises said EDTA in a concentration between 10 and 50 mM.7. The composition of claim 6, wherein the concentration of the EDTA insaid composition is between 25 and 40 mM.
 8. The composition of claim 7,wherein the concentration of the EDTA in said composition is between 30and 35 mM.
 9. The composition of claim 1, wherein said polyol is a sugaralcohol.
 10. The composition of claim 9, wherein said polyol isD-mannitol.
 11. The composition of claim 1, wherein the compositioncomprises said polyol in a concentration between 2.5% and 4%.
 12. Thecomposition of claim 11, wherein the concentration of said poly in thecomposition is between 3.0% and 3.9%.
 13. The composition of claim 1,further comprising a disaccharide.
 14. The composition of claim 13,wherein said disaccharide is selected from the group consisting ofsucrose and fructose.
 15. The composition of claim 1, wherein saidcomposition is injectable through 27 gauge needles or cannula.
 16. Thecomposition of claim 1, wherein said composition polymerizes into a gelmass within between 10 and 120 seconds after exposure to said tissue.17. The composition of claim 16, wherein said composition polymerizesinto the gel mass within between 10 and 60 seconds after exposure tosaid tissue.
 18. The composition of claim 1, wherein said compositionforms a collagen fibril matrix within 10 minutes after exposure to saidtissue.
 19. The composition of claim 18, wherein said composition formsthe collagen fibril matrix within 5 minutes after exposure to saidtissue.
 20. The composition of claim 1, wherein said composition has anosmolality of 280-360 mmol/kg.
 21. A method for augmenting soft tissue,comprising, injecting into a soft tissue deficiency an acid solublecollagen composition comprising, a neutralized solution comprising theacid soluble collagen and EDTA, wherein said composition is injectableat neutralized pH and wherein said acid soluble collagen polymerizesupon exposure to the tissue.
 22. The method of claim 21, wherein saidsoft tissue deficiency is selected from the group consisting ofwrinkles, dermal folds, dermal laxity, skin contour defects, dermal finelines, dermal furrows and dermal unevenness.
 23. The method of claim 21,wherein said injection is into the soft tissue deficiency in lips orfacial skin.
 24. The method of claim 21, wherein said acid solublecollagen forms a collagen fibril matrix after exposure to the tissue andthe matrix remains durable for at least 4 weeks after said injection.25. The method of claim 24, wherein said matrix remains durable for atleast 12 weeks after said injection.
 26. The method of claim 25, whereinsaid matrix remains durable for at least 6 months.
 27. The method ofclaim 21, wherein said injected composition produces regeneration of thetissue.
 28. The method of claim 21, wherein said injected compositionintegrates with matrices of the tissue.
 29. The method of claim 21,wherein said acid soluble composition forms a collagen fibrilmatrix thatfills the soft tissue deficiency.
 30. A biocompatible medical implant,wherein said implant comprises the implant comprised of a polymer ormetal, and a coating of a neutralized acid soluble collagen compositioncovering at least a portion of the implant, wherein the collagencomposition is solidified on the surface of the implant.
 31. The implantof claim 30, wherein said coating is stable on said implant for at least30 days.
 32. The implant of claim 30, wherein the collagen compositionis the composition of claim 1.